1. Field of the Invention
The present invention relates generally to a hinge module for a portable radio terminal, and in particular, to a hinge device that allows a user to readily open a folder with a relatively small angle in a folder-type portable radio terminal.
2. Description of the Related Art
As portable radio terminals become commonplace, diverse functions and designs are developed for them. Diversity of functions as well as small size and lightweight construction becomes significant to the portable radio terminals. To satisfy the customers' demand, the terminals must be less bulky while their functions are maintained at the same level or at an improved level. As a most suitable candidate, folder-type terminals increasingly come to the market and are being developed to be scaled down and have a variety of functions.
A typical folder-type terminal has a hinge module on a hinge arm to raise a folder, or cover, at a particular angle. The hinge module has a hinge shaft installed rotatably within the folder, a hinge cam that retracts backward when it rotates in contact with an angled portion of the hinge shaft, and a spring for pressing the hinge cam within a hinge housing. Angled portions are symmetrically formed at both sides with respect to a valley portion at the center in the hinge cam. While rotating, the angled portion of the hinge shaft runs through the valley portion of the hinge cam to the angled portions thereof, thereby raising a folder or a flip (in the case of a flip-type terminal) at a predetermined angle.
Due to the sidewise symmetry of the angled portions of the conventional hinge cam, a movement stroke is half of the raising angle. This causes no problems to the operation of the flip in the flip-type terminal but increases user inconvenience in the folder-type terminal because the user extends his hand outward to open the folder.